1. Field of the Invention
The present invention relates to cage presses, and more particularly, to spacer elements for use in separating the screen bars of a cylindrical cage press.
2. Prior Art
Cage presses of the type to which the present invention relates are generally constructed of a plurality of rectangular cross section screen bars which are arranged to form a cylindrical cage with the screen bars extending axially along the cage and separated at their innermost edge portions a specific distance which permits oils or other liquids to be expressed from materials being fed through the press. An axially extending screw or worm rotates in the cylindrical cage and compresses the material containing the liquid so that the liquid is forced out between the screen bars.
The spacers are therefore critical in the operation of the press, in that they must maintain the proper gap between the innermost edge portions of adjacent screen bars in order to permit only the oil or other liquid being expressed from the material to pass through these spaces between the screen bars with minimal passage of particles of the material itself. Since the screen bars are of rectangular cross section, the gap from the innermost edge portion to the outermost edge portions of adjacent screen bars is continuously widening and therefore requires essentially a wedge shaped configuration of spacer to produce the necessary gap at the innermost edge portions as well as providing support between the screen bars at their outermost edge portions since the screen bars and spacers take substantial compression loading during operation of the press.
Two examples of prior art spacers for use in cage presses are disclosed, for example, in U.S. Pat. Nos. 3,126,820 and 3,373,680, assigned to the assignee of the present invention. These devices are both generally wedge shaped and since they are made of steel they must be formed, either by a machining or forging operation, to the exact tolerances necessary to provide the desired spacing and support between adjacent screen bars. In addition, in the past means have been utilized for locating and holding the spacers at the proper locations on the screen bars, such as using a projecting stub or tab on each spacer which mates with a corresponding hole formed in the adjacent screen bar.
The cost of producing such spacers has increased substantially due to both material cost and labor cost increases which make them extremely expensive to produce, and in addition, require that substantial numbers be produced at one time in order to make their production more cost effective. Unfortunately, this usually means that the number of spacers that must be produced at one time may be well beyond the number which will be utilized in immediate production demands and replacements, and therefore requires excessive inventory of these parts beyond a reasonable time.